Enable priority for onElementReady and onContentReady on same level

Now it's possible to define a priority for onElementReady to be fired before
onContentReady and vice versa. This works with the jQuery version as well
as the ExtJS.
Move base-call of callOnContentReady into CallOnContentReady

This was done because else callOnContentReady was fired two times on load
Move jquery e.g. ext dependent code into correct file
Centralise onContentReady because it's the same for jquery and ext
Improve test

Check for correct param-object
Check for dynamically added element
Check for visibility options
Add test for change of visibility
Merge pull request #91 from Ben-Ho/3.4-onReady-priority

fix on ready priority